fixes LIBS-54
joo.flash.Run plus Stage modify SWF class metadata
http://jangaroo.myjetbrains.com/youtrack/issue/LIBS-54

Better safe than sorry: fixed two spots where a configuration
object was not copied before fiddling with it.
SWF class's metadata was handed through to Stage's constructor,
which in turn *modified* the object---evil!
Now, joo.flash.Run copies the class's metadata before handing
it out, and Stage no longer modifies its "properties" parameter value.
implements LIBS-55
Allow to create multiple stages on one HTML page
http://jangaroo.myjetbrains.com/youtrack/issue/LIBS-55

Simply reuse one global RenderLoop for all Stages.
That's how it was meant to be used.